On 1 July 2025, the Sentinel-4 UVN (Ultraviolet, Visible and Near-infrared) spectrometer launched aboard the MTG-S1 satellite from Cape Canaveral. cosine is proud to have contributed to this cornerstone mission by developing advanced stray light correction algorithms for the European Space Agency (ESA), helping ensure accurate, high-resolution atmospheric data from geostationary orbit.
The European Space Agency (ESA) has officially launched Sentinel-4 into orbit, marking a major milestone in Earth observation and environmental monitoring. Launched alongside the MTG-S1 meteorological sounder aboard a SpaceX Falcon 9 rocket from Cape Canaveral, Sentinel-4 is now positioned in geostationary orbit, where it will deliver hourly data on atmospheric composition across Europe and North Africa.
Sentinel-4/UVN is a high resolution UVN spectrometer system developed under the Copernicus programme to support the operational monitoring of air quality and climate over Europe and surrounding regions. It provides accurate atmospheric measurements of trace gas concentrations and aerosols.
Stray light, caused by unwanted reflections and scattering within the optical system, can degrade the quality of space-based spectral measurements, impacting radiometric accuracy, spatial resolution and spectral detail.
cosine played an important role in this mission by developing advanced straylight correction algorithms and Calibration Key Data for the Sentinel-4 UVN spectrometer. Developed under ESA contracts, these algorithms support accurate calibration and correction of straylight effects, enabling Sentinel-4 to deliver reliable, high-resolution data from geostationary orbit.
This contribution helps empower scientists, meteorologists and policymakers to monitor air pollution in near real-time, improve forecasting models, and support data-driven public health decisions.
Near real-time air quality monitoring from space
Sentinel-4 is the first UVN imaging spectrometer operating in geostationary orbit. It will deliver hourly observations of atmospheric trace gases and aerosols. As part of Europe’s Copernicus programme, it will provide independent, high-quality environmental data to support decision-making across the continent.
cosine has previously delivered stray light correction capabilities for several space missions, including Sentinel-5 Precursor. With Sentinel-4 now in orbit, we continue our commitment to supporting Europe’s leading Earth observation missions with optical performance solutions and specialised algorithm development.
Watch also: How cosine helps to counter stray light when measuring from space (video)
About cosine
cosine is a leading worldwide company in the development of space instrumentation, such as Silicon Pore Optics for astronomy and remote sensing solutions with onboard analytics for Earth Observation and planetary science. cosine combines physics and technology to bring out-of-the-box solutions to its clients. cosine has been developing and delivering innovative measurement systems for space and industrial applications since 1998. The company operates more than 1,000 m2 of cleanrooms and high-tech assembly facilities to build and test the systems we produce for customers at our headquarters in Sassenheim, The Netherlands and at subsidiaries in Berlin, Germany and Benevento, Italy.
Image credits: ESA
